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Journal of Electrochemistry ›› 2022, Vol. 28 ›› Issue (2): 2108471.  doi: 10.13208/j.electrochem.210847

• Special Issue: Frontier of Electrochemistry • Previous Articles     Next Articles

A Beginners’ Guide to Modelling of Electric Double Layer under Equilibrium, Nonequilibrium and AC Conditions

Lu-Lu Zhang1, Chen-Kun Li2, Jun Huang3,*()   

  1. 1. School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, Anhui, People’s Republic of China
    2. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, Hunan, People’s Republic of China
    3. Institute of Theoretical Chemistry,Ulm University, 89069 Ulm Germany
  • Received:2021-10-26 Revised:2021-12-07 Online:2022-02-28 Published:2021-12-18
  • Contact: Jun Huang E-mail:jhuangelectrochem@qq.com

Abstract:

In electrochemistry, perhaps also in other time-honored scientific disciplines, knowledge labelled classical usually attracts less attention from beginners, especially those pressured or tempted to quickly jam into research fronts that are labelled, not always aptly, modern. In fact, it is a normal reaction to the burden of history and the stress of today. Against this context, accessible tutorials on classical knowledge are useful, should some realize that taking a step back could be the best way forward. This is the driving force of this article themed at physicochemical modelling of the electric (electrochemical) double layer (EDL). We begin the exposition with a rudimentary introduction to key concepts of the EDL, followed by a brief introduction to its history. We then elucidate how to model the EDL under equilibrium, using firstly the orthodox Gouy-Chapman-Stern model, then the symmetric Bikerman model, and finally the asymmetric Bikerman model. Afterwards, we exemplify how to derive a set of equations governing the EDL dynamics under nonequilibrium conditions using a unifying grand-potential approach. In the end, we expound on the definition and mathematical foundation of electrochemical impedance spectroscopy (EIS), and present a detailed derivation of an EIS model for a simple EDL. We try to avoid the omission of supposedly ‘trivial’ information in the derivation of models, hoping that it can ease the access to the wonderful garden of physical electrochemistry.

Key words: electric double layer, equilibrium, nonequilibrium, electrochemical impedance spectroscopy